1. Field of the Invention
The present invention relates to a method for preparing polyester fibers which are superior in water absorbency when compared to those of cotton and wool.
2. Description of the Prior Art
Polyester fibers are usually prepared mainly from terephthalic acid or aromatic dicarboxylic acid, such as 2,6-naphthalenedicarboxylic acid, or their ester derivatives, and ethylene glycol through polycondensation.
Polyester fibers are superior in mechanical properties and thermal resistance, but poor in water absorbency, when compared to natural fibers, such as regenerated cellulose, because polyester fibers have a structure of high crystallinity and few water-affinitive groups, e.g., hydrophilic groups in their molecules. The term "water absorbency" as used herein means the extent to which fiber mass, such as filaments, strands, textile fabrics, knitted goods, non-woven fabrics and the like, absorbs water. Where water absorbency is needed, the use of polyester fibers may cause a problem.
For this reason, active research has been directed to the development of polyester fibers which are of excellent water absorbency while retaining their physical properties.
For example, U.S. Pat. No. 3,329,557 and U.K. Pat. No. 956,833 disclose that polyester can be blended with hydrophilic polyalkylene glycol before spinning. The polyester fibers thus obtained, however, show fairly deteriorated physical properties in addition to not reaching a satisfactory level of water absorbency.
Korean Pat. Publication No. 93-6779 discloses a polyester with an organic compound having polyalkylene or polyamine as a main chain. Disclosed in Korean Pat. Publication No. 86-397 is a polyester mixed with the eluting agent ROSO.sub.3 M (wherein R is an alkyl group containing 1-30 carbon atoms or an alkylaryl group containing 7-40 carbon atoms and M is an alkaline metal or an alkali earth metal) and spun and the fibers are made porous by elution treatment with an aqueous alkaline solution. These polyester fibers are significantly improved in water absorbency, but suffer from a significant disadvantage of being expensive. The additives are highly priced and additional processes increased the high production cost.
It is also known that polyester fibers are provided with hydrophilicity by addition with colloidal silica particles. This causes likewise an increase in production cost.
It is also known that polyester fibers are provided with hydrophilicity by addition with colloidal silica particles. This causes likewise an increase in production cost.